The present invention relates generally to a single-tooth gearing of the type used, for example, for the displacement of movable guide vanes in a hydrodynamic torque converter. Such a gearing is known from U.S. Pat. No. 2,093,003 and U.S. Pat. No. 4,047,383, FIG. 10. In the cited patents, within a reciprocating rod there is provided a recess in one edge of the rod, which can be referred to as a "tooth gap". The flanks of the tooth gap are flat and parallel to each other and are generally perpendicular to the direction of movement of the rod, i.e. the flank angle is zero degrees. A wheel intended for limited rotary motion has a single tooth for engaging the tooth gap, which tooth has the shape of a bolt the "tooth flanks" of which have surfaces that are cylindrical in shape.
The single-tooth gearing known from U.S. Pat. No. 4,047,383 serves to actuate the movable guide vanes of an adjustable hydrodynamic torque converter. Consequently, the maximum stroke of the rod can be relatively short and the maximum angle of swing of the gear can accordingly be as small as about 30.degree. or less. This known construction has the disadvantage that the force-transmitting flanks slide on each other so that there is the danger of premature wear, which results in impermissible flank clearance. In other words, the play-free fit of the tooth in the tooth gap is lost with the passage of time. This danger is present in particular in applications involving the transmission of high forces, as in the case of use in a hydrodynamic torque converter.
In hydrodynamic torque converters it is also known, as shown in German Unexamined Application for Patent DT-OS No. 26 56 142, to provide an articulated connection. If this is done, however, the desired freedom from play and ease of movement can be obtained only at high expense. Furthermore, such a connection is difficult to mount in a torque converter, particularly if the latter is mounted in a gear housing. Finally, although it would be conceivable to use a known rack gearing with involute toothing, as suggested in German Pat. No. 883,379, such a gearing has the disadvantage that a component of force transverse to the rod results from the approximately 20.degree. angle of engagement. This transverse force leads to a bending of the rod and thus to friction in the rod bearings.